The former congressman is running a distant third, well behind former Massachusetts Gov. Mitt Romney and former Pennsylvania Sen. Rick Santorum in the delegate chase.

ByAssociated PressMarch 16, 2012

Republican presidential candidate Newt Gingrich and his wife Callista great supporters at the Lake in the Hills Airport, Thursday, March 15, in Lake in the Hills, Ill.

John Starks/Daily Herald/AP

View Caption

WASHINGTON — Former House Speaker Newt Gingrich said Friday there's probably no circumstance that would lead him to pull out of the Republican race to challenge President Barack Obama in November.

The former congressman is running a distant third, well behind former Massachusetts Gov. Mitt Romney and former Pennsylvania Sen. Rick Santorum in the delegate chase.

Santorum, who is second place but with only just over half as many as delegates as the front runner, has been calling on Gingrich to step aside to allow for head-to-head contest between himself and Romney, who has built his lead largely because the others have split the conservative vote.

Gingrich, a southerner who has won primaries in only two southern states, saw his chances of regaining momentum seemingly dashed on Tuesday when he failed to pull of wins Tuesday in Alabama and Mississippi, where Santorum won and Romney placed second.

Gingrich's only hope now appears that he and Santorum together can deny Romney the 1,144 need to clinch the nomination and take the fight to the convention floor.

Meanwhile Obama's campaign was stepping in the full campaign mode with the President heading out Friday on a concentrated one-day fundraising trip, including in his hometown of Chicago and another in Atlanta for a big-draw event with film producer Tyler Perry and performer Cee Lo Green.

The trip comes a day after Vice President Joe Biden made first major campaign address, labeling Republican candidates seeking the White House as protectors of the privileged and casting President Barack Obama as an advocate for the middle class.

"Mitt Romney, Rick Santorum and Newt Gingrich have a fundamentally different vision," Biden said. "We're about promoting the private sector. They're about protecting the privileged sector."

The speech focused on the economy at a time when signs of a sustained recovery have strengthened Obama's standing and led Republicans to stray from the economic message into deeply divisive social issues like contraception.